聚丙烯酰胺/丙烯酸钾互穿网络多孔水凝胶的制备和性能

以丙烯酸、丙烯酰胺为单体,过硫酸钾为引发剂,N,N′-亚甲基双丙烯酰胺为交联剂,利用水溶液聚合法和乙醇致孔法制备了聚丙烯酰胺/丙烯酸钾互穿网络多孔水凝胶.采用红外光谱(FTIR)和扫描电镜(SEM)等分析技术对水凝胶进行了表征,研究了水凝胶的溶胀行为和吸0.9％NaCl(质量分数,下同)盐水的能力.实验结果表明,该多孔水凝胶具有较快的吸水速率,其最高吸水倍率可达3600g/g,吸0.9％NaCl盐水倍率最大可达120g/g,凝胶粉末能在8min内达到溶胀平衡.     

RAFT一步法制备温度和pH双重响应的多孔智能水凝胶及其性能

通过可逆加成-断裂链转移聚合法(RAFT)一步反应成功合成了温度和pH双重敏感的聚乙二醇甲基丙烯酸酯(OEGMA)-co-丙烯酸梳形/多孔智能水凝胶。采用扫描电镜(SEM)对水凝胶结构进行表征,结果表明,随着加入的致孔剂聚乙二醇(PEG)分子量越大、加入量越多,所得多孔水凝胶的孔径就越大、孔的数目就越多。对水凝胶进行溶胀测试,结果表明,在RAFT试剂的调控下所得凝胶的结构更均匀,因此所得凝胶的溶胀性能较好;经PEG致孔后的水凝胶,其溶胀程度和响应速率相对于致孔前都有所提高;此外OEGMA侧链PEG的长度和交联剂中间链段的长度都对凝胶的溶胀性能有显著的影响。     

多孔聚合物水凝胶的合成及正渗透性能

为了提高聚N-异丙基丙烯酰胺-丙烯酸钠(PNIPAM-PSA)水凝胶汲取剂的正渗透性能,加入致孔剂聚乙二醇(PEG),通过交联聚合法制备了多孔聚N-异丙基丙烯酰胺-丙烯酸钠(PNIPAM-PSA)水凝胶汲取剂。采用红外光谱、扫描电镜等测试方法对其进行了表征,并研究了水凝胶汲取剂的溶胀率、脱水率、水通量和再生性能。结果表明,加入致孔剂PEG(400)后,水凝胶的表面呈多孔结构;当PEG(400)与单体摩尔比为1∶2时,所制备的多孔水凝胶性能最好,与PNIPAM-PSA水凝胶相比,其溶胀率、脱水率和正渗透水通量分别提高了162.26%,15.08%和144.44%;再生的水凝胶,正渗透性能稳定。     

多孔膨润土/丙烯酸/羧甲基纤维素复合凝胶的制备及性能研究

以纳米膨润土、丙烯酸和羧甲基纤维素为原料,N,N’-亚甲基双丙烯酰胺为交联剂,聚乙烯醇(PEG)为成孔剂制备了一种新型多孔网络凝胶。通过红外光谱(FT-IR)、X射线衍射(XRD)和扫描电镜(SEM)对凝胶结构进行了表征。研究了交联剂、引发剂用量和成孔剂的加入对凝胶的溶胀性能的影响。结果表明:交联剂量为0.04wt%,引发剂量为1.5~2.0wt%时多孔凝胶的溶胀性能最佳。在蒸馏水中和0.9wt%NaCl溶液中的溶胀率分别1125g/g和123g/g。成孔剂PEG的加入能使凝胶的溶胀率和溶胀速率明显提高。     

聚（AA-co-AM）／壳聚糖IPN超大孔水凝胶的制备及性能

以丙烯酸、丙烯酰胺为基体,壳聚糖为添加物,N,N’-亚甲基双丙烯酰胺、戊二醛为复合交联剂,利用水溶液聚合法和发泡技术制备了聚(丙烯酸-丙烯酰胺)/壳聚糖互穿网络超大孔水凝胶。采用差示扫描量热法(DSC)、红外光谱(FT-IR)和扫描电镜(SEM)等分析技术进行了表征,研究了水凝胶的溶胀行为和凝胶压缩强度。实验结果表明,该互穿网络超大孔水凝胶具有较快的溶胀速率和较好的凝胶强度。     

温度敏感性P(NtBA-co-AAm)聚合物和水凝胶的合成及表征

以N-叔丁基丙烯酰胺(Nt BA)和丙烯酰胺(AAm)为反应单体,过硫酸铵(APS)为引发剂,在50℃时通过自由基聚合反应合成了具有温度敏感性的聚(N-叔丁基聚丙烯酰胺-co-丙烯酰胺)(P(Nt BA-co-AAm))线型聚合物及水凝胶。为提高凝胶的溶胀性能,以硅胶微粒和聚乙二醇400(PEG400)为造孔剂,合成了一系列大孔P(Nt BA-co-AAm)水凝胶。用差热分析仪分析了P(Nt BA-co-AAm)共聚物的热力学性能,通过红外光谱、扫描电镜表征了P(Nt BA-co-AAm)凝胶的结构。研究了进料中单体配比和交联剂用量对水凝胶溶胀性能的影响以及不同温度下水凝胶的溶胀动力学。结果表明,进料中Nt BA与AAm的摩尔比越高,共聚物及水凝胶的相转变温度越低;增加交联剂的用量,水凝胶的溶胀率降低;大孔凝胶的溶胀率和去溶胀率较传统凝胶有较大提高,同时对外界温度变化的响应更迅速。     

多孔PVA/CNFs复合水凝胶的制备与性能

目的研究聚乙二醇(PEG)的加入对复合凝胶微观结构、溶胀性能和热稳定性的影响,扩大复合凝胶在包装领域的应用。方法以PEG为致孔剂,纳米纤维素(CNFs)为增强相,利用物理交联法制备出多孔聚乙烯醇/纳米纤维素复合水凝胶。结果 PEG作为致孔剂时可制得网络互穿结构的多孔水凝胶,复合凝胶的溶胀度可达到1000,相比于纯PVA水凝胶有极大的提高,同时加入CNFs的聚乙烯醇凝胶与纯的聚乙烯醇凝胶相比具有更好的热稳定性。结论这种有着高溶胀性和良好热稳定性的多孔复合凝胶可用于包装产品的保鲜与物流防护。     

PNIPA/PEG多孔智能水凝胶的辐射合成与性能研究

采用辐射法合成了一系列具有合适相变温度和快速响应性能的PNIPA/PEG多孔智能水凝胶,用红外光谱分析了水凝胶的结构,并测定了水凝胶的溶胀动力学、平衡溶胀率和退溶胀动力学,研究了辐射剂量和成孔剂分子量对凝胶性能的影响.结果表明,PEG分子仅在聚合交联过程中充当成孔剂,不参与反应,反应后被除去;PNIPA/PEG水凝胶的平衡溶胀率(SR)随辐射剂量的升高而减小,其最低临界相转变温度(LCST)在37℃左右,且基本不受辐射剂量的影响;溶胀性能随着PEG分子量的增大而提高.     

快速响应多孔聚丙烯酰胺水凝胶的研制

采用聚乙二醇、聚乙烯吡咯烷酮、CaCO3等不同材料作致孔剂合成多孔聚丙烯酰胺（PAAm）水凝胶，以图提高凝胶的溶胀响应速率。研究结果表明，采用PEG20000、PVP-K30，PEG600作致孔剂对PAAm凝胶响应速率影响不大。用PEG300作致孔剂，凝胶溶胀率随致孔剂浓度的升高，先升高后又逐渐降低，当其浓度为0．045mol／L时，溶胀3．5h，凝胶室温溶胀率提高了15．2％。采用CaCO3作致孔剂可在一定程度上加快凝胶响应速率，随着CaCO3用量的增加，溶胀率先升高后又有所降低。当CaCO3／AAM为5．6％（质量分数）时，溶胀3h后，溶胀率提高了40．3％。     

机械活化淀粉接枝丙烯酰胺/丙烯酸反相乳液聚合动力学

淀粉接枝共聚物是一种新型功能性材料。以机械活化淀粉(mSt)为接枝母体,丙烯酰胺(AM)和丙烯酸(AA)为接枝单体,研究了在淀粉/单体/乳化剂/油/水反相乳液体系中引发机械活化淀粉与丙烯酰胺/丙烯酸接枝共聚反应的动力学,考察了引发剂浓度[I]、单体浓度[M]、淀粉乳浓度[mSt]和乳化剂浓度[E]等因素对表观聚合速率Rp的影响。结果表明,在本文考察范围内动力学关系式为Rp∝[mSt]1.5[M]1.7[I]0.9[E]0.92,单体浓度和淀粉乳液浓度对聚合反应速率影响显著,聚合反应速率随体系温度升高而加快,在45~60℃范围内,聚合反应的表观活化能为89.5kJ/mol,聚合过程中单基终止与双基终止反应同时存在。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.